Added tag 5.0 for changeset 84d936fd18a9
Bumped to 5.1 in preparation for next release.
Rename script template to use .tmpl extensions.

--HG--
rename : setuptools/script template (dev).py => setuptools/script (dev).tmpl
rename : setuptools/script template.py => setuptools/script.tmpl
Bumped to 5.0.1 in preparation for next release.